Geopolímero à base de metacaulim com adição de fibras de sisal

Abstract

In the present context, geopolymer appears as an ecologically viable alternative compared to Portland cement, due to lower CO2 emissions rate, which, the first mentioned is defined as a binder material whose hardening process takes place in alkaline medium. The objective of this work was to produce and characterize geopolymer paste reinforced with long sisal fibers by means of parameters such as flexural strength and toughness. In this work, metakaolin was used as an aluminosilicate source material in addition to a combination of sodium silicate and sodium hydroxide as the activator solution. The brittle behavior, when submitted to flexion, was improved with the incorporation of elongated sisal fibers. In this study, the variables studied were the percentage of fibers in the composite, the ratio between the amount of activator and base material and the cure time. The statistical model of central composite planning was used in order to optimize the results obtained. Subsequently, X-ray diffraction and scanning electron microscopy analyzes were used to analyze the microstructure of the final composite. Optimized values of modulus of rupture equal to 9.20 MPa are found for approximately 2 days of cure in which the activator / metakaolin ratio is 0.59 and the percentage of fiber is 4.34%, by volume. In addition, modulus values of 3.19 GPa are obtained using 5.15% by volume of sisal fiber, an activator / metakaolin ratio of 0.41 and approximately 7 days cure. Finally, the optimization of the tenacity results happens with the use of 5.19% of fiber, in volume, a cure time of 7 days and a ratio between activator and binder of 0.55, reaching a result of 2.09 kJ/m 2. It is concluded, therefore, that the addition of long sisal fibers increases the modulus of rupture, the modulus of elasticity and the toughness of the geopolymer matrix.